public List<UserInfoBaseModel> GetNameByIDList(List<int> UserID)
{
var UserList = LoadRepository<User_Info>()
.GetModel()
.Where(x => UserID.Contains(x.UserInfoID))
.Select(i => new UserInfoBaseModel()
{
UserInfoId = i.UserInfoID,
UserName = i.UserName
})
.ToList();
return UserList;
}
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Lambda的各种语法
{
class Program
{
static void Main(string[] args)
{
List<Student> list = new List<Student>()
{
new Student(){ StudentID = 1, Name = "张飞", Age = 38, Gender = 1},
new Student(){ StudentID = 2, Name = "关羽", Age = 48, Gender = 1},
new Student(){ StudentID = 3, Name = "刘备", Age = 37, Gender = 1},
new Student(){ StudentID = 4, Name = "貂蝉", Age = 20, Gender = 2},
new Student(){ StudentID = 5, Name = "孙尚香", Age = 19, Gender = 2},
new Student(){ StudentID = 6, Name = "甄宓", Age = 17, Gender = 2},
new Student(){ StudentID = 7, Name = "大乔", Age = 18, Gender = 2},
new Student(){ StudentID = 8, Name = "小乔", Age = 18, Gender = 2},
new Student(){ StudentID = 9, Name = "马云禄", Age = 20, Gender = 2},
new Student(){ StudentID = 10, Name = "蔡琰", Age = 21, Gender = 2},
new Student(){ StudentID = 11, Name = "祝融", Age = 17, Gender = 2},
new Student(){ StudentID = 12, Name = "关凤", Age = 16, Gender = 2},
new Student(){ StudentID = 13, Name = "隐藏", Age = 16, Gender = 2},
new Student(){ StudentID = 14, Name = "英雄", Age = 16, Gender = 2},
};
List<StudentExtension> list1 = new List<StudentExtension>()
{
new StudentExtension(){ ID = 1, StudentID = 1, Range = "蜀国", TeacherName = "张三"},
new StudentExtension(){ ID = 2, StudentID = 2, Range = "蜀国", TeacherName = "李四"},
new StudentExtension(){ ID = 3, StudentID = 3, Range = "蜀国", TeacherName = "王二"},
new StudentExtension(){ ID = 4, StudentID = 4, Range = "汉", TeacherName = "麻子"},
new StudentExtension(){ ID = 5, StudentID = 5, Range = "吴国", TeacherName = "王五"},
new StudentExtension(){ ID = 6, StudentID = 6, Range = "魏国", TeacherName = "赵六"},
new StudentExtension(){ ID = 7, StudentID = 7, Range = "吴国", TeacherName = "张三"},
new StudentExtension(){ ID = 8, StudentID = 8, Range = "吴国", TeacherName = "李四"},
new StudentExtension(){ ID = 9, StudentID = 9, Range = "蜀国", TeacherName = "王二"},
new StudentExtension(){ ID = 10, StudentID = 10, Range = "汉", TeacherName = "麻子"},
new StudentExtension(){ ID = 11, StudentID = 11, Range = "蜀国", TeacherName = "王五"},
new StudentExtension(){ ID = 12, StudentID = 12, Range = "蜀国", TeacherName = "赵六"},
new StudentExtension(){ ID = 12, StudentID = 12, Range = "蜀国", TeacherName = "赵六11"},
new StudentExtension(){ ID = 12, StudentID = 12, Range = "蜀国", TeacherName = "赵六22"},
new StudentExtension(){ ID = 12, StudentID = 12, Range = "蜀国", TeacherName = "赵六33"},
};
///select 返回一个匿名函数
var lambda1 = list.Select(i => new { i.Age, i.Name, i.StudentID, i.Gender });
foreach (var item in lambda1)
{
Console.WriteLine(item.StudentID + "\t" + item.Name + "\t" + item.Age + "\t" + item.Gender);
}
Console.WriteLine("select -----end");
///where
var lambda2 = list.Where(i => i.Age < 30).Select(i => new { i.Age, i.Name, i.StudentID, i.Gender });
foreach (var item in lambda2)
{
Console.WriteLine(item.StudentID + "\t" + item.Name + "\t" + item.Age + "\t" + item.Gender);
}
Console.WriteLine("where -----end");
///OrderBy 升序
var lambda3 = list.OrderBy(i => i.Age);
foreach (var item in lambda3)
{
Console.WriteLine(item.StudentID + "\t" + item.Name + "\t" + item.Age + "\t" + item.Gender);
}
Console.WriteLine("OrderBy -----end");
///OrderByDescending 降序
var lambda4 = list.OrderByDescending(i => i.Age);
foreach (var item in lambda4)
{
Console.WriteLine(item.StudentID + "\t" + item.Name + "\t" + item.Age + "\t" + item.Gender);
}
Console.WriteLine("OrderByDescending -----end");
//group子句进行分组
var lambda5 = list.GroupBy(i => i.Age);
foreach (var item in lambda5)
{
Console.WriteLine(item.Key);
foreach (var item1 in item)
{
Console.WriteLine(item1.StudentID + "\t" + item1.Name + "\t" + item1.Age + "\t" + item1.Gender);
}
}
///多表链接
///lambda内连接
var lambda6 = list.Join(list1,
x => x.StudentID,//x对应的是list
c => c.StudentID,//c对应的是list1
(x, c) => new StudentView()//第三个参数对设置返回的数据类型
{
Age = x.Age,
Range = c.Range,
Name = x.Name,
Gender = x.Gender,
StudentID = x.StudentID,
TeacherName = c.TeacherName
}).ToList();
///lambda分组链接
var lambda7 = list.GroupJoin(list1,
x => x.StudentID,//x对应的是list
c => c.StudentID,//c对应的是list1
(x, c) => new //第三个参数对设置返回的数据类型
{
Age = x.Age,
Name = x.Name,
Gender = x.Gender,
StudentID = x.StudentID,
V = c
}).ToList();
foreach (var item in lambda7)
{
Console.WriteLine(item.StudentID + "\t" + item.Name + "\t" + item.Age + "\t" + item.Gender + "我是Key");
foreach (var item1 in item.V)//item.v中是匹配到的数据集合
{
Console.WriteLine(item1.ID + "\t" + item1.Range + "\t" + item1.StudentID + "\t" + item1.TeacherName);
}
}
Console.ReadLine();
}
}
public class Student
{
[DisplayName("学生的ID")]
public int StudentID { get; set; }
[DisplayName("学生姓名")]
public string Name { get; set; }
[DisplayName("学生的年龄")]
public int Age { get; set; }
/// <summary>
/// 1男2女3未设置
/// </summary>
[DisplayName("学生的性别")]
public int Gender { get; set; }
}
public class StudentExtension
{
public int ID { get; set; }
public int StudentID { get; set; }
public string Range { get; set; }
public string TeacherName { get; set; }
}
public class StudentView
{
public int StudentID { get; set; }
public string Name { get; set; }
public int Age { get; set; }
/// <summary>
/// 1男2女3未设置
/// </summary>
public int Gender { get; set; }
public int ID { get; set; }
public string Range { get; set; }
public string TeacherName { get; set; }
}
}
